This is an OCR edition without illustrations or index. It may have numerous typos or missing text. However, purchasers can download a free scanned copy of the original rare book from GeneralBooksClub.com. You can also preview excerpts from the book there. Purchasers are also entitled to a free trial membership in the General Books Club where they can select from more than a million books without charge. Original Published by: National Academy of Sciences in 1977 in 68 pages; Original Identifier: ISBN:0309026229; Subjects: Tomography; Medical / Health Care Delivery; Medical / Diagnostic Imaging;